This invention relates generally to hair removal. More particularly, this invention relates to a method for the temporary removal of hair.
As discussed in U.S. Pat. No. 6,280,438, hair may be removed from selected skin surfaces by the application of intense, wide area, pulsed electromagnetic (light) energy. According to the methodology of U.S. Pat. No. 6,280,438, the energy heats the hair and coagulates the tissue around the hair and follicle without damaging the healthy skin. Pursuant to that prior art disclosure, it is preferable to provide an optically transparent water based gel on the skin prior to treatment with the electromagnetic energy. The gel cools the epidermis but is applied so as not to enter the cavity around the hair follicle, and thus does not cool the hair and the hair follicle. The applied energy then coagulates the hair without damaging the skin.
U.S. Pat. No. 6,280,438 teaches the use of incoherent polychromatic radiation in a wavelength range that penetrates into the skin without being highly attenuated. It is indicated in the patent that wavelengths shorter than 550 nm are not useful because they will be highly attenuated before reaching the lower parts of the hair follicles. Instead, wavelengths in the range of 550 to 630 nm are heavily absorbed by blood and can therefore be used to coagulate the vessels that feed the hairs. Additionally, longer wavelengths, in the range of 600 to 100 nm have a very good penetration into non-pigmented skin and can be used to couple to the melanin of the hair.
U.S. Pat. No. 5,885,273 discloses a method of removing hair that includes producing a plurality of pulses of incoherent electromagnetic energy, which is filtered in accordance with the color of the hair being removed. A flashlamp produces pulses having delays on the order of 0.1 msec to 100 msec, and an energy fluence on the order of 10 to 100 J/cm2. Energy that has a wavelength of less than 500 nm or 600 nm and greater than 1300 nm is preferably filtered out. Light is applied to the treated area in either a long pulse or in a sequence of pulses separated by a delay. The delay and/or pulse length is preferably controlled by the operator to provide enough heat to remove the hair but not enough heat to damage the skin. For example, the pulse length or delay between the pulses should be more than the cooling time of the gel covered epidermis and less than the cooling time of the hair and follicle. Specifically, a pulse length of 50 msec if a single pulse is used or a delay of 50 msec between the pulses if a pulse sequence is used are appropriate values.
In brief, the art using electromagnetic radiation such as pulses of incoherent light is intended to permanently remove hair from selected skin surfaces. The light pulses have parameters such as spectral dispersion, pulse duration and total energy that are selected to destroy the hair follicles in the selected skin area. Understandably, such methods carry a certain amount of risk that the skin may be damaged. Accordingly, the prior art methods of hair depilation are typically intended for use by trained cosmetologists and other professionals. The consuming public is left with few options in removing undesired hair.
It is an object of the present invention to provide a method for temporary hair removal.
A more particular object of the present invention is to provide such a method that is safe for home use.
It is a related object of the invention to provide a method for hair removal, which may replace current home-based methods, for instance, of shaving, waxing, plucking, tweezing, or using depilatories.
A further object of the present invention is to provide such a method that can result in a smooth cleaner hair removal than is possible with razors and shavers.
These and other objects of the present invention will be apparent from the drawings and descriptions herein. It is to be understood that each object of the invention is achieved by at least one embodiment of the invention. It is not necessarily the case that any embodiment achieves all of the objects of the invention.
A hair removal method comprises, in accordance with the present invention, generating a predetermined number of pulses of light each having a predetermined electromagnetic spectrum, and directing the pulses of light towards a skin surface. The light pulses having at least one pulse duration, at least one inter-pulse interval (if the number of pulses is greater than one), and a total energy all predetermined to temporarily prevent a growth of hair through the skin surface for a period of time. Prior to a lapse of the period of time after the directing of the pulses towards the skin surface, the predetermined number of pulses of light are again generated and directed towards the skin surface.
The pulse parameters, namely, the pulse number, the pulse duration(s), the inter-pulse interval(s), the total energy and the spectral distribution(s), are selected in concert to only temporarily prevent the appearance of hair on the treated skin surface. Thus, in contrast to prior methods, which are aimed at completely destroying the hair follicle, the present method contemplates only a partial destruction of the follicles or, alternatively, a destruction of the hair inside the follicles. In either case, the hair will grow and again appear on the treated surface in the absence of additional controlled light application.
The light used in a hair removal method in accordance with the present invention may be incoherent and produced by a flashlamp or other source of incoherent electromagnetic radiation. Alternatively, the light may be coherent and produced by a laser source. In the former case the electromagnetic spectrum of the light pulses is a band of wavelengths, while in the latter case, the electromagnetic spectrum of a light pulse delivered at one time is a single wavelength. In the former case filters may be used to limit the band of transmitted wavelengths, while in the latter case the laser source may be adjustable or tunable for producing wavelengths of different frequencies.
In accordance with the present invention, a user determines the time it takes for the hair to regenerate and reappear on the treated skin surface and reapplies the light pulses prior to the expected time of hair growth through the treated skin surface. More specifically, a hair removal method in accordance with the present invention includes generating a predetermined number of pulses of light each having a predetermined electromagnetic spectrum and applying the pulses of light to a given skin surface, the pulses having at least one predetermined pulse duration, at least one predetermined inter-pulse interval (if the number of pulses is greater than one), and a predetermined total energy. The various pulse parameters are xe2x80x9cpredeterminedxe2x80x9d insofar as they are set or selected prior to the application of the light energy to the selected skin surface. The determination of the different pulse parameters is generally made partially at the time of manufacture of the light-generating device and partially by the selection or selections made by the user. At least in part owing to the application of the pulses to the skin surface, an appearance of visible hair fibers on the skin surface is temporarily prevented. Passing days are then counted between the applying of the pulses to the skin surface and a subsequent reappearance of hair fibers on the skin surface, thereby determining an expected hair regeneration period. After determination of this hair regeneration period, the same pulse sequence is generated, having the same pulse number, the same electromagnetic spectrum(s), the same pulse duration(s), the same inter-pulse interval(s) (if applicable), and the same total energy. This pulse sequence is directed towards the given skin surface. Thereafter, prior to a lapse of the determined hair regeneration period, the light application is repeated with pulses of light having (if desired) the same spectrum, the same number, the same duration, the same inter-pulse interval (if applicable), and the same total energy. It is to be noted that the hair regeneration period may change with time, in part as a result of the light treatments. In recognition of that potentiality, the regeneration time may be recalculated after any given number of treatments. And if the regeneration time does change, the interval between successive light treatments may be adjusted accordingly.
The present invention is thus directed to a method for the temporary removal of hair wherein light application is repeated prior to hair reappearance. This method serves to maintain a smooth and hair free skin surface continuously as long as the light application is repeated in due course prior to the expected time of hair reappearance.
The method of the present invention may be applied to facial hair, leg hair, underarm hair, chest hair, etc., using hand held devices of prior art designs, for instance, with a light source such as a flashlamp, a reflector, one or more lenses, and an application interface such as a skin-contacting crystal. The crystal may function as a cooling element. Alternatively, a separate cooling medium such as a gel may be applied to the skin surface prior to the light application.
Accordingly, the present invention contemplates the use of a hand held device for generating a predetermined number of pulses of light having a predetermined electromagnetic spectrum and for applying the pulses of light to a skin surface, the pulses having one or more predetermined durations, one or more predetermined inter-pulse intervals (if number of pulses is greater than one), and a predetermined total energy. The device is used to temporarily remove hair from a selected skin surface. A period of time for reappearance of hair on the selected skin surface after the using of the device to remove hair from the selected skin surface is determined, for instance, by simply counting the days to hair reappearance after a test light application. Subsequently, the device is used periodically to apply the pulses of light to the selected skin surface at intervals of shorter length than the determined period of hair regeneration, thereby temporarily maintaining the selected skin surface free of visible hair. The regeneration time after any number of treatments may be measured again after any number of light treatment sessions. If the regeneration time changes, the interval between successive light treatments may be adjusted accordingly.
The inter-pulse interval (where the number of pulses is greater than one) may, in different applications of the invention, be anywhere from 1 millisecond to 2 seconds. Generally, the smaller the inter-pulse interval, the greater the risk of damage to the skin. Thus, the smaller inter-pulse intervals should be used only in professional settings. In home-based embodiments of the invention, the inter-pulse interval of a light treatment is preferably greater than 200 msec. An inter-pulse interval of such a magnitude allows partial cooling of the hair follicles and reduces the chances of complete follicle destruction and inadvertent damage to the epidermis. Preferably, the inter-pulse interval is between 200 msec and about 500 msec. An inter-pulse interval of 300 msec is effective.
The total energy applied may be anywhere from 1 Joule per square centimeter of treated skin surface to about 200 J/cm2. Generally, the higher energies entail greater risk to skin integrity and should be used only by skilled professionals. For home use, the total energy applied should be lower, between approximately 5 J/cm2 and approximately 40 J/cm2 of the skin surface. This energy range is appropriate for persons of light skin color. Where the skin color is on the dark side, the upper limit of the total energy applied to a unit of skin surface should be less, for instance, approximately 20 J/cm2.
Generally, it is contemplated that devices used in a method pursuant to the present invention will require a selection of a maximum or total energy to be applied to a skin surface. This requirement typically entails some restriction on the user""s freedom in selecting the magnitudes of other pulse parameters. In a simple device, the user may be able to select only one pulse parameter, namely the total energy. Such a device might, for instance, have high, medium and low settings. In a more complex device, setting of the total energy applied by a pulse sequence will limit the range of options available to the user in setting the other parameters. For instance, once the user selects the total energy and the pulse duration, the number of pulses is determined, provided that the rate of energy production or intensity is not adjustable. If the intensity is adjustable, the user will have some leeway in selecting both the pulse duration and the number of pulses. In that case, the intensity may be automatically controlled by the light-generating device so that the total energy does not exceed the set value.
The duration of the light bursts or pulses may be as little as 1 millisecond or as great as two seconds. The shortest durations and higher energies are recommended for professionally supervised light treatments only. For ordinary consumers or unskilled users, the pulse duration should be longer, preferably above approximately 6 msec and more preferably between approximately 6 msec and approximately 20 msec. A pulse duration of 7 msec is effective.
Pursuant to one embodiment of the present invention, the light of the pulses is incoherent and the spectrum includes wavelengths between about 300 nm and 1200 nm. Longer wavelengths are used for darker skin, for deeper hairs and deeper removal. In some embodiments of the invention, the spectrum of the pulses may be limited to wavelengths between about 300 nm and 550 nm. These embodiments will require a more frequent application of the light energy to effectuate temporary hair removal.
The number of pulses in each pulse sequence or treatment session (as applied to a given skin area) may be between one and ten, while the total duration of a pulse sequence ranges between 1 millisecond and 38 seconds.
As indicated above, the present invention contemplates that some adjustment may be made by the user in the particular operational parameters of the light application device. For instance, a simple hand-held device may have a plurality of settings, for instance, high, medium, and low, where one or more of the operational parameters have different pre-established values depending on the setting. Thus, high, medium, and low settings may vary in the number of applied pulses, the pulse duration, the inter-pulse interval, and/or the total energy applied. A user could start with a low setting to see whether the hair falls out and if not, try the next higher setting. Usually, it is preferable to use the lowest setting which accomplishes the desired result.
It is to be noted that consumer devices may be preprogrammed with automatically operating safety controls which inhibit the user from inadvertently exposing himself or herself to dangerous quantities of light energy. Thus, in a relatively complex consumer product, the user""s setting of one parameter at a potentially dangerous value will cause the device either to limit the selectable ranges of one or more other pulse parameters or to automatically adjust pulse parameters to prevent an excessive rate of energy delivery. For instance, the selection of a small inter-pulse interval may prevent the user from selecting a long pulse duration and/or a small number of pulses or, alternatively, may result in an automatic diminution of the intensity (e.g., via engagement of an intensity-reducing filter).
The present invention provides a method for the temporary removal of hair. The method is safe for home use. The energies used are sufficiently low to avoid skin damage. Because the light is applied prior to the appearance of hair on a skin surface, the skin surface may be maintained in a hairless condition continuously. If the individual wishes to grow hair at any location, this is possible by merely refraining from light application. The present invention contemplates the use of a light applicator periodically, say, at intervals of a week to a few months. In some cases, the light application may be daily, as a substitute for daily shaving with a razor or shaver.
In contrast to shaving, which cuts hairs at or above the skin surface, the method of present invention severs the hairs below the skin surface, thereby presenting a smoother, cleaner, more complete hair removal. In contrast, all conventional methods of hair removal, including shaving, waxing, plucking, tweezing, electrolysis, laser light application, incoherent light application, or the use of depilatories, require the protrusion of the hairs at the skin surface.
It should be understood that the present methodology may be used in professional settings, in spas or salons, by professional cosmetic service providers. Higher energies may be used in such settings. Even higher energies and more complex settings may be used by licensed medical professionals in medical offices.